The present invention relates generally to manufacturing systems and methods. More specifically, the present invention relates to a method and system for fabricating three-dimensional (3D) structures on the micron and submicron scale in a continuous manner.
The demand for new products with more features in smaller areas has resulted in an increasing demand to manufacture smaller features at higher yields. Some conventional techniques for manufacturing periodic structures of three dimensions (also referred to as “3D periodic structures” or, more particularly, “3D periodic nanostructures” where such structures have length, height, and width features in the nanometer regime) are known. By “3D structure” it is meant that the structures can be quasi-periodic in all three dimensions (length, width, and depth). These conventional methods include techniques based on colloidal sedimentation, polymer phase separation, templated growth, fluidic self-assembly, multiple beam interference lithography, multiple exposures of two optical beams and methods based on printing, molding, and writing. Fabrication of 3D periodic structures using a single diffraction element masks have also been demonstrated.
For example, I. Divliansky, et al., “Fabrication of three-dimensional polymer photonic crystal structures using single diffraction element interference lithography”, Appl. Phys. Letters, Vol. 82, No. 11 (Mar. 17, 2003) describe a four-beam interference pattern that is recorded in a photosensitive polymer via a single diffraction element that has a central opening surrounded by three diffraction gratings positioned 120° relative to one another.
In another conventional approach, S. Jeon et al., “Fabricating complex three-dimensional nanostructures with high-resolution conformable phase masks”, PNAS, Vol. 101, No. 34, pp. 12428-12433 (Aug. 24, 2004), describe the use of an elastomeric (PDMS) mask to expose a photopolymer film. In this approach, light passing through the phase mask that has features of relief comparable in dimension to the wavelength of the light generates a 3D distribution of intensity that exposes the photopolymer film throughout its thickness. The phase mask utilized includes a conformable, elastomeric phase mask with features of relief that have dimensions comparable to the optical wavelength. The relief structure is brought in conformal contact with the resist surface allowing for high mechanical and fabrication tolerances. The geometry of this intensity pattern depends on the design (i.e., depth and layout of the relief structures and the index of refraction) of the mask and the wavelength, polarization, and coherence of the exposure light.
However, the conventional fabrication methods are not applicable for fabricating large volume and large area structures of micron or sub-micron periodicity. In addition, these conventional fabrication methods referenced do not present the capability of building different types of lattices with ease of fabrication and with fabrication defect control.